Phonation and the Glottis Cycle

Excerpts from the Paper

The beginning:

Phonation and the Glottis Cycle
Phonation is a complex mechanism involving multiple organ systems and a complex physiological process leading to the rapid closing and opening of the vocal folds in cyclical manner. These cycles are known as the glottis cycle. Each cycle is made up of a closed and open phase. During the closed phase the vocal folds are adducted and during the open phase they are abducted. It results in the production of sound by the vocal cords and the laryngeal muscles. The brain stem reflexes, cortical control and muscular action are the main events involved in phonation according to Rosen & Simpson (2008, p. 7). The laryngeal muscles are involved in phonation and articulation of speech. The complexity of the laryngeal...

The end:

.....e innervated by the external laryngeal nerve. Their function is to increase the tension in the vocal cords by lengthening, tightening and thinning of the vocal cords increasing their resonance frequency. Consequently, the vocal cords are adducted leading to voice production. It is the interaction of all of these different muscles that result in the different sounds that we hear in speech and singing.
References
Reeve, M. (2005). The bernoulli effect and vocal fold vibration. Retrieved from http://www.voicesource.co.uk/article/151, date of download 15 February 2010 (Milton Keynes: Voicesource Publishing, 2005)
Rosen, C.A. & Simpson, C.B. (2008). Operative techniques in laryngology. Retrieved from http://www.springer.com/978-3-540-25806-3